Sensing ultrasonic “pops” utilizing AI and low‑cost microphones could change irrigation and crop care in urban and controlled‑environment farms.
Imagine an urban greenhouse where a bioacoustic early‑warning indicator pings before leaves ever sag. A machine learning model weighs that signal against soil electrical conductivity (EC) (a measure of nutrient concentration in the soil or growing medium) and yesterday’s light recipe, then adjusts a small irrigation pulse. Minutes later, a rehydration signature confirms success—no guesswork, no overwatering, no yield penalty.
That is the thermostat‑for‑plants future Cornerstone Research Group (now doing business as CRG Defense) is building toward: predictive, automated, and accessible to growers without a team of PhDs.
CRG and partners are pioneering a deceptively simple idea with big implications: listen to plants. Using ultrasonic microphones and machine‑learning, CRG’s Acoustilytix Intelligent Bioacoustics System detects tiny, high‑frequency acoustic emissions—think microscopic “pops”—that occur when water‑transport tubes in plant stems form gas-filled cavities or bubbles under stress.
Those pops show up before leaves droop or change color and without touching soil or stems. For growers, especially in urban agriculture and controlled environment agriculture (CEA), such as greenhouses and vertical farms, earlier insight can mean smarter irrigation, higher yields, and lower labor costs.
“You can hear the plant’s own voice… an early indicator of water stress that arrives before any visible symptoms,” said Eric Rombokas, Research Engineer, CRG.
What is Acoustilytix & How the “pops” work
Acoustilytix began as a cloud platform that analyzes ultrasonic vocalizations in laboratory rodents. CRG adapted the platform to agriculture, where the same core strengths—sensitive microphones and robust signal classification—can translate hard‑to‑hear data into actionable plant‑health insights.
The system combines non-contact ultrasonic microphones placed near crop canopies with AI models trained to detect and classify the acoustic emissions that signal plant stress or recovery, producing early warnings, stress indices, and ultimately closed-loop irrigation triggers.
Plants draw water from roots through xylem vessels and release it via transpiration. Under water stress, tension rises in those vessels; air bubbles form and collapse, creating ultrasonic pops. Humans can’t hear them, but mics can. Because this signal is directly tied to plant physiology, it’s not a proxy like ambient temperature or soil moisture—it’s the plant itself “raising its hand.”
CRG has also observed a rehydration signature—a distinct pattern when a stressed plant receives water—providing growers with confirmation that an irrigation event met the plant’s need.
Hear it yourself: Ultrasonic pops, slowed to human‑audible audio.
Why It’s Different (and Complementary)
Growers often track environmental factors like vapor pressure deficit (VPD, which reflects how quickly plants lose water to the air), temperature, and soil EC.
“It’s unique: not a proxy, but a window into the plant’s physiology that plays in harmony with everything else on the farm,” said Rombokas.
Because the sensors are non‑contact, installation is straightforward:
- Placement: Mount microphones above canopy rows or zones; no probes in wet media, no corrosion risk.
- Coverage: Continuously monitor blocks or beds; expand by adding mics.
- Interference: Operates in the ultrasonic band, where it’s relatively quiet; AI filters out non‑plant noise (pumps, fans, clanks).
CRG’s priority is reliable, low‑cost hardware paired with the existing software—simple enough that no expert is required: “as easy as a smartphone analytics app.”
Additionally, in a NASA Phase I SBIR study on lettuce (a staple crop for space and CEA research), CRG showed that stressed plants emitted more acoustic (AE) pops than well‑watered controls. The AE signal appeared at onset, before visible wilting or camera‑detectable morphology changes. A rehydration AE followed watering, indicating successful recovery. This approach detects plant stress sooner than cameras or soil sensors can, while also working alongside those tools to provide a fuller picture of crop health.
Where AI/ML Adds the Most Value
AI/ML enables predict‑then‑act workflows that cut water and nutrient waste, preserve quality, and stabilize yields under volatile conditions.
- Detection & Classification: Distinguish plant pops from background ultrasound.
- Prediction: Use time‑series histories to forecast stress before it escalates.
- Closed Loop Control: Drive irrigation setpoints or alerts based on AE thresholds.
- Generalization: Expand across crops, growth systems (soil, hydroponics), and stressors (drought, nutrient imbalance, pest feeding).
“Two things make this moment ideal: a clean ultrasonic band and ML that can separate stressed‑plant pops from everything else,” said Rombokas.
What began as a tool for studying lab rodents is now giving farmers a way to literally listen to their crops. By tuning into the ultrasonic pops of stressed plants, CRG and its partners are helping growers shift from reactive fixes to proactive care. In a world where every drop of water and every square foot of growing space matters, bioacoustics offers a practical path to smarter irrigation, steadier yields, and more resilient food systems.
As part of the Precision Urban Agriculture Initiative, led by Parallax Advanced Research and the Ohio Aerospace Institute, we are spotlighting innovative ag-tech companies like CRG that are pushing the boundaries of what’s possible in sustainable farming. By highlighting advances such as bioacoustic plant monitoring, the initiative showcases how emerging technologies can strengthen urban food systems and inspire broader adoption. This work was performed under the following financial assistance award 60NANB24D146 from U.S. Department of Commerce, National Institute of Standards and Technology.
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About Parallax Advanced Research & the Ohio Aerospace Institute
Parallax Advanced Research is an advanced research institute that tackles global challenges through strategic partnerships with government, industry, and academia. It accelerates innovation, addresses critical global issues, and develops groundbreaking ideas with its partners. In 2023, Parallax and the Ohio Aerospace Institute, an aerospace research institute located in Cleveland, OH, formed a collaborative affiliation to drive innovation and technological advancements across Ohio and the nation. The Ohio Aerospace Institute plays a pivotal role in advancing aerospace through collaboration, education, and workforce development.
About CRG
Cornerstone Research Group (CRG Defense) is a research, development, and product company with capabilities spanning aerospace, advanced sensors, materials, power, and more. The Acoustilytix platform reflects CRG’s specialty: making sense of new kinds of data and translating them into practical solutions.